Wearable display optics are commercialized for use in a range of applications, such as military, entertainment, and industrial applications. Virtual Reality (VR) systems, such as the OCULUS RIFT(TM) VR device familiar to those knowledgeable about VR systems, provide an immersive, digitally generated display with a sizable field of view (FOV). VR devices are particularly popular in gaming applications.
In order to provide superimposed image content in the FOV, AR systems employ some type of combiner element. The combiner is commonly the optical element that is positioned closest to the eye, at a distance from the eye termed the “eye relief”. The balance of the optical elements of the AR display are then forced forward, further away from the eye, in order to clear the combiner. One combiner approach, for example, uses a curved, off-axis, semi-transparent mirror. While this arrangement has some advantages for forming virtual images, the display FOV is constrained in size and performance, largely due to the need for optics separation from the eye and due to the off-axis angles that are used.
By comparison with AR optical systems, VR systems that do not use a combiner can have sizable field of view. The OCULUS RIFT VR system referred to previously had originally consisted of a display similar to that used for a smartphone, with a suitable eyepiece or ocular. The eyepiece is centered on the display so that the system does not suffer off-axis aberrations comparable to those found in conventional AR systems.
Among challenges for augmented reality (AR) imaging are providing a wide field of view and good image quality for display content, such as the OCULUS RIFT VR system exhibits, with the additional capability for viewing the object scene without cumbersome constraints of earlier AR designs for providing the needed eye relief.